Reenforced concrete construction



' DecIS';t 1927.

l-I. L. KATZ REENFoRcED CONCRETE coNsTnucaIoN 2 Sheets-Sheet 1 FiledSept. 14. 1926 Fly. Z

H. L. KATZ v REENFoncED CONCRETE CONSTRUCTION Filed Sept. 14. 1926 2:Sheets-Sheet 2 Fly-5 Patented Dec. y13, 1927.

j UNITEDI STATES PATENT- -oFFicE. i

HARRY L.' xn'rz, oE BALTIMORE, MARYLAND. l.

y. REENEOECED CONCRETE CONSTRUCTION.

Application.aleaseptembe14.1926. yjserialiro. 135,378.

y Y This invention relatesl toreenforced concrete construction, and morespecifically to reenforcing :concrete beams, girdersy and slabs againstdiagonal tension orweb shear,

5 bondand tensile stresses.

Y rDiagonal tension or web shear is anfimportantfactor in reeni'orcedconcrete desigan. In the present dayfpractice, the shear and` resultantdiagonal-- s'tress are assumed'to be :carried by theconcrete itself, bytheflon- Vgitudinal steel, and by vertical or inclined stirrups. Thevalue of stirrups 'as diagonalY tension .reenforcement is questionable,and.

vthe vresults of experimentsrdo no't'justi'fythe amount of importancethat' has been vlgiven this method 'of reinforcement.

A second important factor is bond stressf Failure ,'by slipping joccursWherethe 'shear and therefore the bond ystress `ifs,greatesta namely atYthe supports. In practice, resistance to slipping, in addition to thatinherent frombar friction and grip due tof toVthe.developmentofsecondary .stresses Ywhich Acausefthe beam tocrack,with'c'onsequentffailure. y A f p A'Lprimary,object is to provideadequate reenorcenient by av Isimplified construction,

V40 ywhereby to obtainv maximum strength with .minimum expenditure Aofmaterial;

*Another object is totransmit the diagonaltension or web shear from theconcrete` to fthe web of alight'weight steel beam, eliminatingg therebytheuse of stirrups.v

Still another object 'is to produce a me rchanicalanchor at--the ends ofthe tension .bar s, therebyy preventing vsecondary stresses lin Athebeam Vwhich are usually due to bar 59 vanchorage, and eliminatingslipping fait;

ure.

Other Aobjects and attendant' advantages -associated with this inventionwill be later onreferred tol or become apparent `from' the,

description following; and said. invention may-bebrieiiydeiinedasconsisting in the novel features of construction, combinations setkforth and thereafter the lsub-joined'claims. y lIn thefurther disclosureoi the inven-Q 'vtersely stated by vand arrangements of' partshereinafter fully tion,` reference is to behad to the accom,y

panyingshfeets Aoi explanatoiy drawings, constitutlng'a part of thisspecification, and

`inwhich .corresponding Iparts' are distinguished,A y the same Aindicesthroughout the several rviews'. Y

lIn the drawing, Figure 1 yis 'a fraginentaryk plan view of a floor, thesupporting columns appearing in section.y .v i. Y"

.Figuresl and v3 are .vertical sectional views taken yrespectively on'lines 2-2 and 3..-3ofFig. 1. j i.

Figure Zlis an enlarged verticalise'ction on line t-4:, Fig. 1..f

.Figure 45 is a lvertical lsection l on" line 5-'5,fV

Fig.. 4,' and Y Y y Figure 6 is a similar enlarged View thru lined-,6,Fig. 1. i

Y In thefparti'c'ular embodiment of thein vention Vchosenv `torillustrating its characteristics, but whichis not toibel too'conserva-Ativelyl regarded,*tlie same embodies va concreteil-loer slab10'supporfted by suitable col- Vumns, 11, 'which inaylbe' inthe for-m of'H- column having web portions 8 `jand'flanre n Yportions 9. VOthertypesA:of conventionai co uinnsections may lbe utilized.v The 4vcolumns arelireprooiedVv wi'thconcr'ete, as indicated .ati-7. Depending from fthe"iloorY slab between.

adjacent pairs of columns are `girders 412 and beams 13.. Similarintermediateb'eams 14 extend' between the girders V12, as clearly shown.in Figure 1.V V'lh'e'beains or girde'rs 'may be considered*V asT-b'eflmsi in which a 'I portion of the slab acts as a flange. The

Vposes Vonly at ,N-A (see Fig. V6), may be VVconsidered as slightlybelowuthe'slab, tho, as well known,its locationvaries accordingneutralaxis, indicated for illustrative pnrto conditions. Tensionmembers 15 of usua construction serve to reenfo'rce the slab."

Referring to Fig. 6, numeral 16 designates ay steel Ibeam embedded inthe concrete beam .14. The beam '16 isfofligh't Weight' constructionvand preferably'of the type i1-A lustrated in the U. S. patent toLockhead,

VNumber 1,554,108,A issued Sept. 15, 1925.

Light steel beamsjcapable of functioning as' Ythe instant case havefo'nlyf recently.uw

been purchasable on the open market. It is important to note that thesection 16 is positioned below the neutial axis, that is to say, in thatportion et the `concrete subjected to tension. Since concrete is strongin conipression, it is unnecessary to reeiiforce the compression portionabove the neutral axis.

I am aware that it heretofore has been pro-- posed to `utilizeI-sections in concrete beam reenforcing, but these sections arerelatively large and heavy, and the upper portions of the steel areencased in the compression flange of the concrete, well above theneutral axis. The concrete beam is thus in et feet split vertically intwo, resulting in a less etlicient structure. It will thus be seen thatby positioning;r the beam 16 below the neutral axis, I avoid theaforesaid splitting of the beam, and obtain thereby `importantfunctions, both in economy of steel and elii ciency of the concretestructure. Further, by using small light sections 16 `so proportioned asto be below the neutral axis, the number of sizes of sections necessaryto cover a wide variation in conditions is nia-- terially reduced, sinceby slight `variation in raising or lowering of the steel beam, `thestrength of the concrete beam can iiicreased or decreased, all `of whichwill be readily apparent to those conversant with y the art.

As shown, the gii'ders 12 and beams 13 are also provided with lightsteel sections 16. Reentorcementsfor the girders are preterablyoi' twinformation, see Figs. Band 5.

The sections 16 are rigidly connected at their ends with the columns orbeams they frame into, thru the instrumentality of angle brackets 17 andbolts or rivets 18, see Figs. 4 and 5. The column and beam connectionsare designed to carry the entiie end reaction. Windbraeing (not shown)may be provided for wherever necessary or re'- quired, in the mannercommon to structural steel construction.

The function of the sections 16 is to trans* mit the diagonal tensionoi'web shear from the concrete to the web 16 of the respective sections.Flange portions 16 ot the sections aid' in resistingr the tensilestresses.`

The use of stirrups and other shear `carriers `is thereby eliminated,and in eliminating these devices, it will be obvious that the members 16function as shear members independently of the concrete.

Tension bars 2O and 21, which may be of any conventional shape, hereshown as flat,` are positioned as shown. Upper bars Q0 may` if desiredbe bent up as shown in Fig. 4:, thereby aiding the steel beams incarryingr stresses due to diagonal tension.

The bars 20 and 21 have their terminal portions bent :is shown andclamped between the angle brackets 17 and the adyacent column or beamsupport, see Figures l and 5,

the securing elements serving as a common securing means for both thebarsand Isec tions. It is oi the greatest importance that the bars besecurely anchored at the ends. By securing the bars to the beams andcolumns in the manner shown, the elastic limit of the steel may bereached without causing secondary stresses peculiar to thc conventionalmethods ot bar anchorage, thereby preventing` shrinkage tension anddeveloping;r the full tensile stress of the bars. Failureliiy slippingis avoided, thereby eliminating sel rions cracks at the tension-sideo'tthe beam, namely at the points,whereishear and therefore the bondstress is the greatest.`

It is to be noted the present construction utilizes steel columns inconnection with `the reentorced concrete construction. proofing `T isnot relied upon to carry the oad on the columns, tho it assists and`insuies a stronger structure. By climinatini;` concrete and utilizingsteel for the columns, I am enabled to avoid the conventional InAmethodsl ot bar anchorage, and employ my have provided a very light,i'igdsteel slrelemi ton frame designcdto carry the entire dead load andforming a` complete and independent steel structure whichsnbsequentlyybecomes reenforcement for the concrete,` producing a rigid,ireproof, monolithic structure. V It furnishes level supports forhanging the Wood forms, avoids the necessity for shoring, and enablesthe steel to proceed independently and aheadoit' the concrete. y. f

It will be further apparent that a mono- 1m lithic skeleton reenforcedconcrete structure is provided in which provision `is made for all thestresses and strains taking place,` except those of direct compression,which of course, are taken care of by the concrete per se.

By the term concrete as herein used,` I

mean to include any fireproo cementitiousw.

inaterialsuitable for use in building purposes.

It is to be understood the invention isnot limited to the constructionshown, since various modifications may be made without departing fromthe spirit and scope of. thel appended claims.

I claim: i 1. Reenforcements `for a concrete beam comprising separateshear and tension members, said members embedded in said beam entirelybelow the neutral axisthereof, said shear member functioningindependentfof the concrete and said tension member anchored at its endsindependent Vof the concrete, and fmeans for supporting said beam.

. beam of I-section in shape.V

4. Reenforceinents fora concretev floor beam, including aklongitudinally extending metallic shear beam embedded in theconcrete-and functioningindependently of tension reenforcement,said'shea'r beam being positioned entirely below the Lneutral aXis andfunctioning independent of the concret-e, and means for supporting saidbeam.

5. A concrete beam having reeiiforcements therefor and a support, saidreenforcements including a lshear member and tension resistinfr means,said shear member beingY positioned entirely below the neutral axis andfunctioning independent of the concrete, and means connecting said shearmember to said support. f

6. A concrete beam having reeiiforcemeiits i therefor, steel supports,a` shear member functioning independent of the concrete, longitudinaltension bars, and means rigidly connecting terminal portions ofsaid'te'nsion bars to said supports, to thereby provide a mechanicalanchor functioning independent of the concrete to eliminate slippingofthe bars.

7. The construction in claim 6, wherein said shear member is entirelybelow the neutral axis.

n 8. -In a .reenforced concrete structure, a longitudinal tension memberhaving end anchorage independent ofconcrete, and a separate longitudinalshear beam operative independent of the concrete, whereby the concreteis relieved of all shear carrying and end anchorage function, and meansfor supporting said structure.

9. The construction in claim-8, wherein the shear beam ispositionedentirely below the neutralaxis. l v

lO. Reenforcement construction`V for l con'- .crete beams supported bysteel columns, comprisin'g va plurality of longitudinal tension members,said members havingftheir Vends vertically,V bent, means includingbrackets rigidly connecting said' ends 'with said columns to therebyeffect a mechanicaly bond Vindependent of the concrete and wherebytensile stresses are transferred to the steel columns vat, said endconnections, a longitudinal shear beam VAfunctional independent of theconcrete, said connectingmeans also serving yas common connecting'meansWhereby the shear beam is secured at its ends tol said columns, saidconnections being rigid and designed to, carry theentire end ,re-

action. Y v

11. The construction in claim 10, wherein Vsaid shear beam is positionedentirely below the neutral axis. p

HARRY `L. KATZ.

